1. Field of the Invention
The present invention relates to a used wire cutting device for a wire cut electric discharge machine, which cuts a used wire electrode into pieces by a mechanically or magnetically moved blade and drops them into a container.
2. Description of Related Art
It is already known to provide a wire cutting device for cutting a used wire electrode into pieces by a mechanically or magnetically moved blade and dropping them into a container, on a discharge side of a wire cut electric discharge machine (see JP3-49831A or JP2982485B, for example).
Normally, when used wires are cut by a movable blade and a fixed blade, the blades become worn out and unable to cut wires in a certain time. Generally, the time to replace a blade is determined on the basis of the time for which it has been used. However, the degree of wear of a blade varies depending on the diameter and material of a wire used. Further, even if wires used are the same in diameter and material and blades used are the same in material, the life of the blades varies depending on makers. Hence, it is difficult to determine the time to replace a blade only on the basis of time.
The technique for estimating the life of a blade is known in JP2003-340684A, although it is not for a wire cutting device for wire cut electric discharge machine but for a saw blade. The technique disclosed in JP2003-340684A is intended to deal with various materials, shapes and sizes, and determines the life of a blade on the basis of many elements. Hence, the relation between the area of cut and the amount of wear is shown by a polygonal curve. Further, the amount of wear that corresponds to the life varies depending on the material and diameter. Thus, many elements are considered to determine the life.
There exists no technique of determining the time to replace a blade of a wire cutting device provided in a wire cut electric discharge machine to cut a used wire electrode into pieces and drop them into a container. By the technique of estimating the life of a saw blade disclosed in JP2003-340684A, it is difficult to determine the life or correct the life determined, since the life is determined on the basis of many elements.